Oh, grannytomine, what a horrible experience your family members went/are going through. I just trust that the dad loves the kids and is taking good care of them. But I understand the concern about their being married off, eventually, etc. And, of course, the mom's pain in not having her children (and the GPs' pain, too, of course, and so forth.) They will be in my prayers.
I'm not sure how talk of baby equipment came into this, but I agree with the idea that it depends on the relationship and whether or not there have been other issues surrounding the new/coming baby. If the younger parents think the GPs have been trying to take over and have balked at unsolicited advice or unwanted gifts of equipment for their own home, they're likely to see this as another "take over" move. (By "this," I mean the GPs fitting their home out with lots of baby stuff. If the GPs have always shown respect for the parents as adults and asked about the equipment ("Should we?"... "What brand of this or that do you prefer?"), then it's more likely the parents will be ok with it, maybe even delighted (great to have less things to bring when visiting)! I kept some baby stuff at my house when my grands were little - diapers, burp cloths, wipes, a pack & play for them to nap or rest in and had a couple of gates where needed, as they got older. But except for the gates (necessary for safety) and maybe wipes (even if just for my own use, LOL) , I wouldn't have had any of this if the parents weren't cool with it.
Ok, I have DDs, no DSs, so no DILs - and maybe it is easier with DDs than DILs cuz there's a history there and lots of love and so forth. But some GNers have been CO by there DDs and some MNers seem to have CO their DMs. (I'm using the "D" here cuz I hope there's still love there, on some level, as some EGPs here have said there is in their hearts). So it's not always easier with DDs and I don't think those of us with DDs only can be complacent, FWIW.